+notrack not removed if DNS server doesn't return CNAME record

I've had various issues with +notrack not being removed from URLs over the past year or so rendering the received messages to be un-viewable or un-clickable.

The original problem I believe was related to connections to the database server being reset due to a misconfiguration that would sometimes cause `Postal.tracking_available? && @domain.track_clicks?` to be false in `lib/postal/message_parser.rb`. When that happened, `insert_links` would not be called and therefore `part.gsub!(/(https?)\+notrack\:\/\//) do`... would not be executed to replace `+notrack`.

Recently I inadvertently started routing my tracking domains through Cloudflare's proxy services and when I did that, they would no longer return a CNAME record for my tracking domains (they would only return an A record). So, at some point, postal detected the lack of CNAME as a DNS error and updated the tracking domain to have `dns_status=Missing`. In that case the message parser would ultimately not call the `insert_links` function.

Clearly it's very important to have everything set up and running correctly. I'm just wondering if it would be possible to do the `+notrack` replacement no matter what before a message is sent. I'd rather have messages be sent that will work for the recipient rather than have tracking.